Solar energy arrays on farmland no longer means that the land will be taken out of production as large ground-mounted panels take up valuable farmland, disturb soils and offer neighbors unsightly views. Instead of large parcels of land dedicated exclusively to solar panels, modern agrivoltaics combines solar energy generation with agricultural crop production, habitat restoration and conservation, plus it offers farmers economically viable opportunities to generate power – whether for on-farm use or on a commercial scale – without sacrificing valuable acreage.
Solar & Grazing
It wasn’t that long ago that grazing poultry or small ruminants between and around solar panels was generating attention. This dual-use approach allowed standard solar arrays to be erected on pasture and livestock to graze between and under the panels. Panels provided some shade to keep animals cool, and the animals grazed the grass, decreasing the need for mowing.
Today, solar arrays are being designed to accommodate cattle. Not only are arrays, such as the ones at the University of Minnesota’s West Central Research and Outreach Center, generating energy to power barns – they are also higher off the ground, allowing larger animals to graze below. The raised height also allows the sun to reach the grass below at least part of the day, having little impact on its growth, while allowing cattle access to shaded areas throughout the day, reducing heat stress.
Raising the height of solar arrays might allow more grazing to occur, but it still looks and functions like traditional solar arrays. If for aesthetic reasons, or for environmental ones, ground-mounted horizontal arrays won’t suit, there are now vertical solar panels designed to function as a fence in dual-use grazing situations.
Having much less of a footprint on the pasture, installing these arrays allows livestock to graze as usual, right up to a solar-powered electric fence, which can be placed alongside the vertical panels to keep the cows away.
According to William Kanitz, owner-consultant of et-sun LLC, their solar fences capture 30% more energy than traditional ground-mounted horizontal panels. They are also less expensive to install, are only eight inches wide – requiring little land to be sacrificed – and are designed to be safe in hurricane-strength winds. They don’t need to be cleared of snow and ice accumulation and are cooler than horizontal arrays, so there is significantly less power decline due to panel heating than seen in horizontal panels.
These vertical arrays also can be moved. These solar fence panel arrays can be temporarily installed on leased land and moved by hand up to four times per year, or portable panels can be installed on a trailer for temporary applications. The permanent panels are anchored into the ground and are useful as perimeter fencing for grazing livestock systems.
Et-sun’s vertical panels have been approved by the USDA for the REAP program, Kanitz said, offering farmers and small rural businesses grant and loan money for renewable energy projects. Learn more at tinyurl.com/462snrt8.
The vertical panels can also be used in lieu of horizontally mounted panels in other on-farm applications, including in field and row crops, to generate power – which is then stored in a battery – for electric farm equipment (including tractors and other large machinery), to power the dairy barn or for food processing, Kanitz said.
“It’s going to change agriculture,” he said of vertical solar arrays.
Newer horizontally mounted solar array designs utilize panels which can tilt or rotate with the sun, capturing more energy. These tracking panels not only capture more solar energy, they change the amount of sun available under the array, potentially allowing better crop yields.
Alternatively, horizontally mounted solar panels can be used to provide some water retention benefits by shading crops in arid regions and reducing evaporation. Working under horizontal arrays can also provide relief to humans, reducing the risk of heat stroke. Research into crop production and solar array integration is ongoing.
Even orchards are going under the cover of solar panels. Three dimensional agrivoltaic research modeling has shown the potential for solar panels to protect orchard crops from hail and sunburn, keep orchards productive and healthy and be economically viable through solar energy capture. While on-the-ground research is in the early stages, there may soon be solar arrays over fruit and nut trees, or in vineyards and other small fruit acreage, providing benefits to the farm, the food system and the environment.
The Sue A. Carter Research Group in the Physics Department of UC-Santa Cruz has led research on wavelength selective photovoltaics (WSPV), enabling the efficient capture of solar energy which also promotes optimal plant growth in an economically viable manner.
Soliculture grew out of that research, and offers customizable greenhouse solar panel applications for high tunnel or greenhouse growers, with both commercial and off-grid capabilities. These panels capture solar energy and allow light to pass through for greenhouse plant use. They optimize the light by altering green light waves – which plants don’t use in photosynthesis – to valuable red ones, enhancing plants’ growth while augmenting solar power production too.
More Than Grass
Commercial solar power arrays traditionally are sited on grass. But there is ongoing research and establishment of pollinator habitats around arrays, using native plants for habitat restoration. One such example is the Plains, GA, commercial array on former President Jimmy Carter’s family land. The seven-acre site was part of a 25-acre field formerly used for peanuts and soybeans, now surrounded by a neighborhood. Various pollinator seed mixes, as well as grass plots, have been planted here under the 3,852-solar panel array, and research is ongoing.
Restoring native plant habitat and providing pollinator-friendly environments adds ecosystem value to the land on which solar arrays are sited while protecting soil health and reducing maintenance concerns such as mowing. It also provides a visually appealing addition to a community, all while generating renewable energy. Maintaining honeybee hives around solar arrays planted to pollinator habitats allows farmers to generate economic benefit.
Today, commercial scale on-farm solar energy can be beneficially incorporated with livestock grazing, pollinator habitat, row or field crops and even orchards with minimal disturbance or lost access to farmland. Smaller on-farm but off-grid solar arrays can efficiently power farm vehicles and equipment and provide energy to greenhouses, cold storage units or packing houses.
Rather than displacing farmland and disturbing soils, today’s solar panels and arrays are being utilized in sensible, innovative manners to promote sustainable agricultural and conservation practices.
by Tamara Scully
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